What is the name of the central part of the atom?

The nucleus

The atom is composed of three basic parts: protons, neutrons, and electrons. Protons are positively charged subatomic particles that, along with neutrons, make up the nucleus of the atom. The number of protons in each atom is unique to each element.

For example, helium will always have two protons and if there is an element with three protons, it cannot be helium. Neutrons are neutral subatomic particles that are also in an atom's nucleus.

The nucleus is the central core of the atom, around which the electrons (negatively charged subatomic particles) orbit.